Process for making trimethyl acetic acid



Patented Mar. 2,6, 1935 ES 1." du Pont me D91 1 Application fle' -Nemours 8e flompanyizwilia; corporation oi Delaware Serial at 658361 14Clalms'. (01; 2605-1 16 This invention relatesto tnesynthesisor mmethyl acetic acid-and more particularly to" the preparationof trimethylacetic; acid' by theinteraction of isobutanol and carbon monoxidez formed from tertiary butyl: iodide by means of the: cyanide in accordwith' the reaction disclosed 10 by Butlercfi 4114873. It-hasaisobeen prepared by the oxidationof pinacolinet Such methods otpreparation-are necessarily expensive due-prinlrrte e el t ve hi c s traw ia r- Qwing; to the many -impcrtant "uses to which hist pwfra id -adantedam yc i have not, been exploited extensively dueto'- its:

relatively high] cost, it is obvious that a process for thepreparation of trimethyl acetic a'cidfrom raw materials,- which are;-'atf present, readily available and which will be even more readily available in the near future, will be of far reachingimportancein thisart;

-If? is-anobject ofthe present-invention t'o pr'o vid'a9pro'cess' for thesyntl'iesis 1 oftriniethyF acetic acid fromsimpler and less costly raw ma'terial'sthan have previously been; used; other" objects and? advantages will hereinafter appear;

r have found that triinetl'iyl ac'eticacid" can; bep'rbduc'ed by the reacnomor-steam, carbon monoxide, and isobut'an'ol; I i The reactiommay-be conducted in the presence or absence"ofsteam;

with'steahi-the' acid is usuallyi produced in" greater quantitytli'an the butyl 'estei ofthe acid; in the absence of steam the reverse is:' generally true;

'I'he reaction apparently proceedsin accord'withr; 7

" 5 reaction proceeds over awide range oftemperatures while working under these pressures, al-

the equation- 8 i I 1 on-omoH-Loononowo oooa while-Lone would expect to obtaiirnot thet'rimethyl acetic acid but beta bet'a; dimethyl' propi onicacid. a mat r ls able ware'readily available f-rom a number of sources.

, Thus, isobutanol obtained from the fermentation of grain or potatoes or from the catalytic hydrogenation of carbon oxides under pressure in accord with the description of such processes to be found in U, S. Patents Lazier 1,746,781, Larson 1,844,587, Williams Re. 18,302. It is preferable,

for the sake of avoiding undesirable by-products,

that the alcohol be employed in a relatively high degree of purity. The carbon monoxide required for the synthesis may conveniently be derived 'Irimethyl-nacetic; acidsvariously Cal ed pivalic acid, dimethyl-propane acid andr having the" cific' 'ratios or the alcohol to carbon monoxide? and steam. Generally speaking, the desired refor use in the process from; ariouscommercialsourc es," such as, -for; 1

example, water gas,.- producer gas, etc,, by liquethe best results be relatively pure, it beingipare ticular-lydesirable to avoid; thepresence therein of sulfur compounds, metallic carbonyls and the like. v v

, factionor-other means,,and should likewise for Inert: gases, such asnitrogen,-methane,andicar this being advantageous in some cases from the standpoint of controllingthe temperature of-the exothermic reactionand-"ofl limiting the expense thereof,=wher'e itmay be; dQsiredtorestrict the j overall conversionlof thereaction for the sake? 15 l of enhancing the, relative yieldof the desired acid, When employing one or more ofthelabove gases asinert carriers to effecttheseadvahta esi it'orthey should generallybe present in amounts constituting, approximate1 '4m or more by van; ume

of th'el whole. gaseous "mi i'iture, including. the steamy-5 L The. relativeproportions' of'the reactants can:

bexva'ried although it has been'foundthatin ordertoavoidi sidereactions involving the alcohol. I

it'jisi; advantageous to work with steam and carbon monoxide excess with respect 7 to the alcohol.

Concentrations of the latter withinthelran'gebi from 1 to 10% by volume of'tlie total reaction? with pressures of 500 atmospheres or more; have given particularly goodjr'e'sults; Higher concen-' tration's may be used, however, it desired, but

under such conditions correspondingly lower" pressures should be employed.

The use of pressures in excess'o'f atmospheric, say, from2 5-900 atmospheres, is preferred. The

though the optimum temperaturefvaries withgspeactioncan be obtained at from 200-500" C. From the standpoint ofpractical operation the tem- 5 perature'should not be; so lowgthat the; reaction;

rate. is uneconomical, nor so; high as -'to 1 result"; in undesirable by-products by decomposition; of the alcohols and the acids produced. From this i ate satisfactorily at from 275- -3750. a

Point O w the process has been found to oper- The following example will illustrate a method of practicing the'invention, altho the invention is not limited by the example: A gaseous mixture consistingof 83.4

and 0.4% hydrogen chlorideiall in per cent, by weight, was passed, at a. pressure of approxi- 6f ca Y bon monoxide, 12.1% of steam, 4.1% of isobutanol,

acetic acid, 2.8% or the butylll est er or trimethyl approximately 300 C. into'a catalytic reaction chamber containing activated carbon. Acondensate was obtained, upon cooling the converted 'gases, containing an upper and a lower layer.

The upper. layer contained: 77.8% 1 trirnethyl acetic acid, and 20.3% of'unconverted isobutanol.

. charcoal alone has proven disclosed invention;

acetic acid.

The lower layer contained 4.8% formic acid approximately 0.6% of thebutyl este of tri-' methyl acetic acid. y A number of catalysts may be employed to accelerate the reaction and include, generallyrinorganic acids that are; not substantiallyvolatilizedf at the temperature of the synthesis-,;e.ig.,-;acids and boron. Activated tobe agood catalyst;

of phosphorus, arsenic,

for the reaction and when used. in conjunction with the inorganic acids, particularly fso. 'fTh'e'i following catalysts may likewise be employed; calcium chloride, cadmium? phosphate, flsilica tungstic acid, zinc chloride, calcium chloride, -calcium iodide, sodium bromide, and-potassium chloride. Infactfmycatalyst-capable o1 pro I reaction in the presence 0 a? ydrogen' halide as moting the synthesis of aliphatic acids from'carbon'monoxide andalcohols" aresu'i'table.

The apparatus, which may be employed for conducting these-reactions, may be of any conventional type and preferably one-'in'whichthe; temperature of exothermic reactions readily controlled'at the desired value. "Owingd v to the corrosiveaction of the trimethyl acetic'acid,

produced, the interiorof theconverter'and con duit leadingltherefro m' should preferably be-pro-f tect edy- This maybe accomplished by glass or glass linedfapparatus, or byjcoating the inner surfaces of, the apparatus [with chromium, or silver, or using for the constructionoi this equip? nient acid-resisting alloys of, for example, molybi" denum, cobalt, 'tun'gsten;manganese; or nickel.

Froma consideration ofthe above specification it will be realized: that any process {or the preparation of trimethylacetic acid by the interaction oi isobutanol withfcarbon 'monoxidef will come; within the scope ofthis invention, providingfthe reaction be effected in 'accordfw l hFthe abovei I claim:

3 "1; The processor reacting isobutanoland car-I jbon monoxide and thereby producing trimethylj;

acetic acid substantially inaccord ,withthe 101 lowing equation:

,cH, e

2. The process of reacting isobutan'ol' and'carthereby" producing trimethyl qoxide, characterized in that the reaction is effected under a pressure withimthe range, 01 m 00 a mosp er s m eta empe a u bon monoxide and 3. grrne process'of' reacting isobutanol and carv bonfmonoxide in the presence of a catalyst capaisle ofpromotingthe synthesis 0! aliphatic acids from carbon monoxide and alcohols and thereby T ,producingtrimethyl acetic'acid.

can be" 4. A process of producing trimethyl aceticacid' I from isobutanol, steam, and carbon monoxide,

characterized in that, an excess of steam and carbon monoxide is employed with relation to the isobutanol.

5. In e se producing trimethylgacetic acid ,irom is'o'butanol, ste

oxide," characterized in that the reaction is efiectedunder a pressure within the range oi from 25 to 900 atmospheres.

, :1 6=. I nflla. process" of producing" trimethyl acetic acid from isobutanol, steam, and carbon monoxide, characterized; in that the reaction is feflectedat a temperature within the range of 7 Ina process fertile preparationoi trimethyl acetic iacid 'iromisobutanol, steam, and carbon monoxide, cha'racterizedin that the reaction is effected in the presence of a catalyst capable 01 ot, aliphatic acids from promoting the synthesis carbon monoxide and alcohols."

"81 In a process-tor the preparation of trimethyl acetic acid 1mm isobutan'ol; steam ma cal-ban monoxide,- thes'tepwhich comprises eflecting' the' 2g I the catalystthereiori *9. In a process for the preparation of trimethyl; Q

acetic acid from isobutanol, steam, andwcgbon monoxide, the-"step which Comprises Electing the reaction 'in'thepresenceoi a I I activated carbon as the catalyst insurer.

10. one process of" 'reagents; isobutanol and carbon monoxide b tne-mmmmneous action of,

heat and pressure a'ndv" thereby'flproducingfqtri- F methyl acetic acidsu v antially'in accord with v 1 1, The process ofreactirig hon.-m n xi e byt efs mu a u 's t o b -h a n p e s re n .fli reb Pro c n t im yl 1 ,Th croc sa li t s dc carbon, monoxide and alcohols-and ,thereb'y producing-trimethyl acetic acid. i.

relation to the isobutanol. 14.In a process of producing trirnethyl acetic acid from 'isobutanoLf steam;v andcarbon monwithin the raneof zoo-500 c.

bon monoxide bathe hnu e e i ec n e andjpressure in the presenc e 01a catalyst capable, ,ofpromoting synthesis, of. aliphatic acids from 1311a process of. Pm u i r iipEt Sl can? acid from isobutanol, steam, and carbon mon- V V a oxide, bygthe simultaneous action of heatand: I 1 :1: 1 pressurewcharacterizedsinithat an qexcess otg o 0 o o a H ,v T) 1 steam and carbon monoxide is employed-with 

